1 tbsp water
6 cups (1.5 L) baby spinach
1 cup ricotta
1 cup grated parmesan
salt and freshly ground pepper
4 sheets pasta
2 egg yolks (optional)
2 cups tomato sauce (see Easy Tomato Pasta Sauce in the Mains-Pasta section)
1/4 cup Parmesan cheese
Heat 1 tbsp of water in a medium pot on high heat. Add spinach and cook just until wilted. Drain and squeeze out any water. Coarsely chop. Mix with ricotta and 1 cup of grated Parmesan and season with salt and pepper. If adding egg yolks, add now. Over low-medium heat, heat the spinach mixture for 5 minutes.
Place cooked pasta sheet on plate, in middle, add spinach mixture and fold over. Drizzle tomato sauce over and sprinkle with Parmesan. Repeat with remaining pasta and serve.